Crush washers are used to seal fluid or gas connections such as those found in an internal combustion engine. For instance, crush washers are used to provide a seal between an oil pan and a drain bolt to prevent engine oil from leaking. Similarly, crush washers are used to seal the connection between a transfer case pan and a drain bolt to prevent gear oil from leaking and between a transmission pan and a drain bolt to prevent transmission fluid from leaking. There are many other applications within an internal combustion engine where a crush washer may be utilized.
When the drain bolt is tightened onto the pan, care must be taken to avoid over-torqueing of the bolt as this may cause the pan to become cracked. The crush washer provides a margin of safety in that the crush washer is designed to deform when a torque sufficient to prevent leaking has been applied to the bolt. The deforming of the crush washer allows the bolt to be over-torqued a slight amount before damage to the pan occurs. There are instances, however, when the deformation of the crush washer may go unnoticed. In such instances, if torque continues to be applied to the bolt, then this margin of safety is overcome and the pan may become damaged and/or leak.